In an information apparatus to which the technique of the VM: Virtual machine is applied, a guest OS being a virtual OS (Operating System) operates on a hypervisor. The guest OS performs the processing of a program using a virtual CPU to which a physical CPU (Central Processing Unit) is virtually assigned.
As an example of the technique to assign a physical CPU to a virtual CPU, a technique to use an address conversion table that determines the correspondence between a logic processor (virtual CPU) and a physical processor (physical CPU) has been proposed. Specifically, in the proposed technique, a table representing the correspondence between the logic partition address space that the logic processor is able to access and the logical address space, and a table representing the correspondence between the virtual address space that the guest OS included in the logic partition and the physical address space, is able to use directly are set. Then, the control OS (hypervisor) updates these tables arbitrarily according to the situation, making possible to realize the switching of the correspondence between the logic processor and the physical processor without making the guest OS recognize the switching of the physical processor.
Meanwhile, as another technique, a technique that enables, in a time sharing an access from the guest OS to MMIO (memory mapped IO) register information even in a condition in which no physical processor is assigned to a logic processor has been proposed. Specifically, in this technique, copy information of the MMIO register corresponding to the logic processor is held in the memory in both the condition in which a physical processor is assigned to the logic processor corresponding to the guest OS and the condition in which no physical processor is assigned to the logic processor. Accordingly, the guest OS is always able to access to the information of the MMIO register, making it possible to avoid processing delay.
Here, in the technique to assign a physical CPU to a virtual CPU to realize the program processing in the guest OS, when a switching of the virtual address space being the processing target of the virtual CPU, the hypervisor has performed the following process. That is, the hypervisor has switched the physical address space of the processing target of the physical CPU assigned currently to the virtual CPU in tandem with the switching of the virtual address space being the processing target of the virtual CPU.
Patent Document 1: Japanese Laid-open Patent Publication No. 2006-127462
Patent Document 2: Japanese Laid-open Patent Publication No. 2006-350531